Automatic S/PDIF Selector

These days there is an increasing number of devices that have a digital audio output, for example digital cable tuners, satellite receivers, DVD players/recorders or game consoles/computers. It is often the case that the existing receiver doesn’t have enough coaxial S/PDIF inputs to accommodate all these devices, or the receiver is at the other side of the room from the TV and other equipment, and we’d rather not lay three or four separate S/PDIF cables along the skirting boards. This clever little circuit gets round these problems in an ingenious way. It doesn’t need a mains supply nor does it have any external switches.